Impact of Physical Activity on Left Ventricular Mass and Lipid Metabolism

Prospective study on the structural and functional changes in the heart of adult women assessed by echocardiogram and in lipid metabolism that occur in response to physical training. Using echocardiogram we will characterize the early determinants of "athletic remodeling". We will also assess the effect of intense physical training on lipid metabolism, focus on HDL subspecies and function.

Left ventricular hypertrophy, defined as an increase in the mass of the left ventricle may occur as a physiologic response to exercise (athletic remodeling aka "athletic heart"), but is most frequently encountered as a pathological manifestation of cardiovascular disease. The early determinants of athletic remodeling in the general population are largely unknown. In order to longitudinally explore the early determinants of athletic remodeling, we will recruit from the community, physically untrained women who have volunteered to run a marathon. We will prospectively assess left ventricular mass and function by echocardiogram during three consecutive stages/visits:

• Baseline: prior to starting intense physical training
• Trained: at the end of at least 12 week training period, prior to running the marathon.
• Post-marathon: 6 weeks after running the marathon.

In addition, exercise impacts lipid metabolism and short-term exercise is known to increase HDL levels in plasma. Human HDL is structurally heterogeneous, comprising at least sixteen discrete species. It has multiple functions, pertinent to cardiovascular medicine such as the ability to accept effluxed cholesterol from the artery wall, culminating in sterol uptake in the liver. This "reverse cholesterol transport pathway" is thought to prevent the accumulation of cholesterol in the artery wall. We will assess the clinical and genetic determinants of the HDL response to physical exercise.

Community sample. Participants will be recruited by invitation to volunteer in the study.

Inclusion Criteria:

• Healthy adult women, aged 18 years or older
• Voluntarily signed up to run a marathon or a half marathon for the first time
• Normal to mildly elevated blood pressure (systolic blood pressure < 140 mmHg and/or diastolic blood pressure < 90 mmHg)
• Hormone replacement therapy and birth control pills are allowed, provided they have been on a stable dose for more than 3 months and no change in dose is planned for the duration of the study
• Capable and willing to provide written, informed consent for the study

Exclusion Criteria:

• History of cardiovascular disease (cardiomyopathy, heart failure, ischemic heart disease, stroke, TIA, peripheral vascular disease)
• Change in body weight more than 10% over the past year
• History of significant medical conditions, including respiratory, gastrointestinal, neuromuscular, neurological or musculoskeletal problems interfering with exercise.
• Autoimmune or collagen vascular diseases, chronic anemia,
• Malignancies in the past 5 years, with the exception of treated skin or breast cancer that did not require treatment with chemotherapy.
• Diabetes
• Pregnancy or recent delivery: delivery date less than 3 months prior to enrollment
• Lipid lowering medications (statins, niacin, resins)
• Fish Oil supplements are allowed, provided dose has been unchanged for 3 months prior to enrollment and no change in dose is planned for the duration of the study.